The invention relates to groups of multiplexed communication networks such as for instance so-called local interconnection networks (or LIN (for “Local Interconnection Network”)) or CAN type networks (“Controller Area Network”) or FlexRay type networks, especially used in some automotive vehicles.
A “group of multiplexed networks” is understood here to be a group of at least one multiplexed communication network comprising at least one device (called a slave device in the case of a LIN network) connected to a bus to which is also connected a master control device (called master device (or node) in the case of a LIN network). The master device is specifically tasked with putting to sleep or waking of the devices of the group of multiplexed networks.
When the devices (or nodes) of a group of multiplexed networks are placed in sleep mode (at the request of the master device), they automatically wakeup upon detection of an activity on their bus. This activity requiring waking of other devices normally originates from a device, potentially from the master device, but can also be generated by the presence of parasites. It is indeed assumed that an activity exists on the bus when a so-called “recessive-dominant” transition is detected followed by a dominant state during a time greater than a threshold (several tens of μsec in the case of a CAN network). The dominant state (“or logical low”) is the electrical level of the network corresponding to a logical “0”. Inversely, the recessive state (or “logical high”) is the electrical level of the network corresponding to a logical “1”. The logical level “0” is called dominant level because it takes priority when several devices try to impose different levels. Consequently, any voluntary or involuntary phenomenon generating a recessive-dominant transition followed by a dominant state during a time greater than the threshold is considered by a device as an activity that must lead to its wakeup.
When the master device detects an activity on the bus, it must immediately determine whether another device is effectively at the origin of this activity. If the master device obtains a wakeup confirmation from an activating device, it will then authorize the devices to stay awake. In the contrary case (parasites) the master device must command the controlled devices to return to sleep mode. It is clear that if the parasites originate from a defective device of one multiplexed network of the group, all the devices of the multiplexed network of the group can become the object of alternating sleep and wakeup phases, causing overconsumption of electricity by the network, which in turn can provoke discharge of the battery (in case of installation in an automotive vehicle) and this discharge can be accelerated in case the wakeups propagate to the other multiplexed networks of the group.